# VFR

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```					Pearls of Wisdom – VFR

1. Landing Distance With A Tailwind
Increase the normal landing distance by 50% with a 10-knot tailwind. Double it with a 20-knot tailwind
e.g.    Normal landing distance from performance charts = 700 ft
Tailwind = 10 knots
New Landing Distance = 1,050 feet

2. Approach Speed In Windy Conditions
Add half the gust factor to your approach speed when landing in windy conditions.
e.g.    Approach Speed (1.3 Vso) = 65 knots
Winds 10 gusting to 20 knots (gust factor 10)
New approach speed 65+ 5 = 75 knots

3. Distance To Begin Descent
Determine altitude to lose (drop zeros) then multiply by either 4, 5, or 6 depending on groundspeed to get
distance from destination to begin descent at 500 fpm. 120 kts=4, 150 kts =5, 180 kts=6
e.g.    Altitude to lose at 120 knots = 4,000 ft.
4 x 4 = 16
Begin descent at 500 fpm at 16 miles

4. Emergency Turn Back To The Runway
To complete a 180º turn in most light singles takes at least 700 feet at a 45º angle of bank. Therefore
calculate minimum turn back altitude before takeoff by adding 700 feet to local field elevation. This is
your minimum altitude below which you should not attempt a turn back to the field and instead elect to
land straight ahead. At airports where there are intersecting runways this rule of thumb may not apply.

5. Stall Speed At Various Bank Angles
Stall speed increases in proportion to the square root of the load factor. Since load factor increases with
bank angle, a relationship can be determined between stall speed and bank angle as follows, using as an
example an airplane with a no flaps stall speed (Vs) of 53 knots.

Load Factor         Sq Root            Stall speed
Level Flight           1                 1.00             53 knots (53x1.00)
60º Bank               2                 1.41             75 knots (53x1.41)
70º Bank               3                 1.73             92 knots (53x1.73)
75º Bank               4                 2.00             106 knots (53x2.00)
80º Bank               5.76              2.40             127 knots (53x2.40)

6. Rolling Out Of A Turn
Begin rolling out of a turn at half the bank angle degrees prior to reaching your desired heading.
e.g.     Bank Angle = 30º
Desired Heading = 360º
Begin Roll Out at 345º
7. Calculating Standard Rate Turn
Standard rate is about 15% of the airspeed in knots.
e.g.    IAS = 120 knots
120*15% = 18
Standard Rate is 18°

8. Calculating Radius of Turn
Because of the increased load factor and stall speed increase much beyond a 45° angle of bank, a
practical limit of 45° angle of bank should not be exceeded. Since radius of turn at a constant angle of
bank is a function of groundspeed, the formula at a 45° bank angle is groundspeed squared divided by
11.3. This becomes important when considering turns in a confined space (like a canyon). Consider two
examples at different speeds, same 45° angle of bank.
2
Groundspeed 100 knots: 100 /11.3 = 885 feet
2
Groundspeed 150 knots: 150 /11.3 = 1,991 feet
Therefore an airplane turning at the same angle of bank will take about 1,100 feet more to complete the
turn.

9. Calculating Take Off Distance
Standard runway light separation is 200 feet, so takeoff distance can be calculated by counting them

10. TAS Increase With Altitude
Airspeed increases about 2% per 1,000 feet of altitude.
e.g.   TAS is determined to be 120 knots at sea level
At 10,000 feet it will be 20%`
2%*10=20%
120+20%=144 knots

11. Calculating Pressure Altitude
To calculate pressure altitude, subtract current pressure setting on the altimeter from 29.92. Add 3
decimal places to the result and add that amount to the MSL altitude.
Or if you are in the airplane, just set altimeter to 29.92 and read the pressure altitude off the altimeter.
e.g.     Altimeter Pressure 28.68 (AWOS)
Standard Pressure 29.92
---------
Difference          1.24
Add 3 decimals 1,240

Therefore pressure altitude is 1,240 feet greater than MSL elevation

12. Calculating Density Altitude
For each 1°C above standard temperature, add 118 feet to the pressure altitude. Conversely for each
1°C below standard temperature, subtract 118 feet.
e.g.    Calculate Density Altitude at 1,000 feet pressure altitude when the temperature is 32°C
Since standard temperature is 15°C, the difference is 17°C more so you will be adding.
17 x 118 = 2,006
Therefore add 2,006 to the pressure altitude of 1,000 = density altitude of 3,006 ft.

13. Quick Distance Estimate on a Sectional Chart
Use two fingers for 10 miles on a sectional chart, four fingers for 20 miles. On a terminal chart use two
fingers for 5 miles, four fingers for 10 miles.
14. Flight Service and Flight Watch Frequencies
122.0 Nationwide Flight Watch Service. Call up by name of Flight Watch (consistent with ARTCC area)
and location relative to nearest VOR.
Call: New York Flight Watch, Archer 2245W, 10 north of Yardley
122.1 FSS receive only, listen through VOR. Call up by name of FSS, location relative to nearest VOR,
and frequency you’re using.
Call: Williamsport Radio, Archer 2245W, 10 north of Yardley on 122.1
122.2 FSS send and receive. Call up by name of FSS, location relative to nearest VOR, and frequency
you’re using.
Call: Williamsport Radio, Archer 2245W, 10 north of Yardley on 122.2
122.6 FSS send and receive, available in some areas only. Call up by name of FSS, location relative to
nearest VOR, and frequency you’re using.
Call: Williamsport Radio, Archer 2245W, 10 north of Yardley on 122.6
All FSS stations operate 24/7. Flight Watch operates from 6AM – 10PM

15. Calculating Hydroplaning Speed
Hydroplaning can occur with as little as ten thousandths of an inch of water on the runway. Use this
formula to determine hydroplaning speed.
Calculate square root of tire pressure. Multiply this number by 9 for take off hydroplaning speed and 7.7
for landing hydroplaning speed.
e.g. Tire Pressure 30 PSI
Square Root of 30 = 5.5
Take Off Hydroplaning Speed 9 * 5.5 = 50 knots
Landing Hydroplaning Speed 7.7 * 5.5 = 42 knots

On landing you must slow to at least 42 knots before applying brakes to avoid the potential for
hydroplaning.
On take off you should try to rotate by 50 knots to avoid the potential for hydroplaning.

Note: This rule of thumb will vary depending on the condition of the tire and type/condition of runway.

16. Calculating Best Glide Speed
For Single Engine Fixed Prop: Multiply Vs (bottom of green arc) by 1.6. That’s best glide at max gross.
To get best glide for the weight of the airplane, multiply the max gross number by the percentage of max
gross of the airplane. For single engine retractable gear, use 2.0 as the multiplier instead of 1.6 and
follow the same procedure.
e.g.    Archer 180
Vs 52 knots
Best Glide (Max Gross) 52 * 1.6 = 83 knots
Airplane weight is 80% of max gross
Best glide is 83 * 80% = 66 knots for that weight
Pearls of Wisdom – IFR

1. Stabilized Decent for a 3° Glide-Slope
A stabilized decent can be thought of as a 3° glide-slope, similar to most ILS approaches or VASI/PAPI
systems. A 3° glide-slope is always equal to a 300 ft/nautical mile decent rate, regardless of speed. If a
300 foot/nm decent is the goal, then knowing your ground speed will allow you to convert into the actual
decent rate in feet per minute that you can read on your VSI. Just take half your ground speed and add a
zero. For glide-slope of ½° more or less than 3° add or subtract 100 feet per minute. For 1/4° add or
subtract 50 feet per minute.
e.g. Groundspeed = 90 knots
90/2=45(0)
Decent Rate = 450 ft/minute

2. 60:1 Rule in Determining Decent Gradient
Here’s how the so called 60:1 rule verifies the decent rate for various decent gradients – the most
common being the 3% gradient used in ILS approaches and VASI/PAPI glide paths. First, take a circle
that has a radius of 60 nautical miles and determine the circumference by applying the formula 2 pi r
(2*3.14*60). This yields 376 nautical miles as the circumference of the circle. Now stand that circle so
that it is one long line 376 miles in length. If you now divide 376 by the number of degrees in a circle
(360), you get 1.05 miles for each degree. Since 1.05 is close to a mile, we know that 1 mile per degree
is close enough.
So if 1°is 1 mile in height at a distance of 60 miles, then at 1 mile it would be 6,072 feet divided by 60,
which equals 101 feet. Therefore each degree of gradient at 1 mile equals 100 feet. So therefore, a
3°glide slope equals a 300 feet per nautical mile.

3. 60:1 Rule in Determining VOR Distance Off Course
At 60 miles, each degree of needle deflection equals 1 mile off course. At 30 miles, each degree of
needle deflection equals ½ mile off course.

4. Calculating the Visual Decent Point (VDP)
The VDP is the point at the MDA beyond which a stabilized decent is not possible. It is therefore helpful
to know where the VDP is on any non precision approach. Use this formula: Height Above Threshold
(HAT) divided by 300 = VDP.
e.g.    HAT = 600 ft AGL
VDP = 600/300 = 2 miles from runway

5. Converting Climb Gradient From Feet Per Mile to Feet Per Minute
Formula is climb rate (feet per nautical mile) times (groundspeed divided by 60)
e.g.   Groundspeed = 90
Climb Gradient = 400 Ft/Mile
(400) x (120/60)
400 x 2 = 800 ft/min
Climb Gradient is 800 Feet Per Minute

Another method is to use the E6B flight computer and put groundspeed over 60 and read fpm over fpm
on outer scale

6. Partial Panel Compass Turning Error
Use UNOS – Undershoot North, Overshoot South. When turning to a northerly heading stop short
(undershoot) desired heading. When turning to a southerly heading, overshoot (go past) desired
heading. Use the latitude as the number of degrees to overshoot or undershoot.
e.g.    You are turning right to a heading of 350° and your latitude is 40°. Stop your turn when the
compass reads 310°
7. Important Checklists

Approach Checklist
Do the following checklist at least 10 miles outside the FAF PSPS HAR
Primary Com Frequency Set
Secondary Com Frequency Set
Primary Nav Frequency Tune, Set, Identify
Secondary Nav Frequency Tune, Set, Identify
Heading Check (Set DG)
Atis then Altitude
Review Approach Chart

Landing Checklist
Do the following at least 5 miles outside the FAF PFGUMPS
Power – Reduce to desired setting
Flaps – Employ or not
Gas – On proper tank
Undercarriage – Gear Down if appropriate
Mixture – Rich
Pitch – Full Increase
Switches – Fuel Pump, Landing Light, GPS/VLOC Switch, Marker Switch

8. Instant Position At A Glance Using VOR
With a FROM indication, your position is on a radial located in the top quadrant opposite the needle. With
a TO indication, your position is on a radial located in the bottom quadrant opposite the needle. For
example, assume the OBS is oriented with 360° at the top, the indication is FROM and the needle is left.
Therefore your position is on a radial in the right top quadrant opposite the needle (0°-90°). If in the same
example everything was the same but the indication was TO, your position would be on a radial in the
bottom right quadrant

9. Have I passed the Radial Yet Using VOR
With a FROM indication, the needle always points to the VOR before you get to the radial dialed in the
OBS. This only works if the radial on top of the VOR is on the same side of the VOR as the side you are
on. The other method which works regardless of where you are is to look at the 90° intercept and that
heading will take you to an intercept of the radial dialed in at the top. If this is not your approximate
heading (or almost the opposite) you have passed it.

10. Time to a VOR
Without GPS or DME, how do you calculate how long it will take you to get to a VOR. First, center the
VOR needle with a TO indication, then twist the OBS 10° to either side. Turn 10° to intercept it and count
the seconds until the needle centers. Subtract a zero from the total seconds and that’s how many
minutes it will take to get there. Don’t forget to re-center the needle and fly the appropriate course.
e.g. You count 120 seconds until the needle re-centers, drop the zero and find that you will arrive at the
VOR in 12 minutes. From this information you can also calculate how far you are away. For most
training airplanes, multiply the time by 2 to get 24 miles for this example.
Pearls of Wisdom – Weather

1. Thunderstorm Avoidance
Circumnavigate thunderstorms by at least 20 miles. Hail is most likely to be thrown out on the downwind
side. Tornadoes are most likely to be present on the upwind side. These are the reasons for the 20-mile
margin of safety.

2. Convective Weather Likelihood
Here are three ways you can tell if thunderstorms are likely.
 Dew point of 65°F or more in the morning
 Lifted Index of –3 or greater (more negative) - Composite Moisture Stability Chart
 K Index of +30 or greater (more positive) - Composite Moisture Stability Chart

3. Cloud Prediction
Cloud bases can be predicted by taking the ground temperature and dew point spread in °C and dividing
by 2.5. The result (adding 3 zeros) is the expected height of the bases. This formula works best in rising
air because unsaturated (rising) air, cools at 3°C and the dew point decreases at .5°C per thousand feet.
Therefore the temperature and dew point converge at 2.5 °C per thousand feet.
e.g.    Temperature = 15°C
Dew Point = 10°C
Height of Bases = 5/2.5 or 2(000)
Therefore cloud bases would be expected at 2,000 feet.

4. Important Moisture Stability Value
The composite moisture stability chart provides useful information about the likelihood a severity of
convective activity. The two most important values are the K Index and Lifted Index. An easy way to
remember warning values is 24/7. If the Lifted Index (indication of the stability of the atmosphere) is -7 or
more negative or the K Index (indication of the amount of moisture in the air) is +24 or more positive,
there is a high probability of significant convective activity.

5. Wind Direction and Weather
If the wind is from your left, you’re flying into an area of worsening weather.

6. Estimating Wind Direction Aloft
Winds aloft are usually 40° to the right of the surface winds

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 views: 44 posted: 4/12/2010 language: English pages: 6